Broaching machine



C. J. HALBORG BROACHING MACHINE Jan. 18, 1949.

Filed Jan. 25, 1945 4 Sheets-Sheet 1 INVENTOR. C .7, HaZZa/g,

/7 T /T/V Y5.

J 1949- c. J. HALBQRG BROACHING MACHINE 4 Sheets-Sheet 2 FiledJan. 25,1.945

INVENTOR J3 flaXZarg a) C'arl BY FT a/TNEys Jan. 1 1949. HALBORG2,459,697

' BROACHING MACHINE Filed Jan. 25, 1945 4 Sheets-Sheet 3 C. J. HALBORGBROACHING MACHINE Jan. 18, 1949.

Filed Jan, 25, 1945 4 Sheets-Sheet 4 gzn/ E L I I 4 INVENTOR.

6 135/456 (hr! 17. flaZ/p/y BY r Patented Jan. 18, 1949 to ColonialBreach Company, Warren Township, Macomb County, Mich acorporation. of

Delaware Application January 25, 1945, Serial No. 574,509-

2'7 Claims.

lhe present invention relates to surface broachingmachines.

It has-beenthe standard practice in surface broaching to construct aspecial broach for each machining operation with the proper toothstepping and the proper number of teeth to complete a given machiningoperation on a particular workpiece in one pass of the breach over thework. Standardization of broaches has not been possible because thedepth of out per tooth (i. e. the amount of step between successiveteeth) must be selected for each job since it depends onthe material ofthe workpiece, the length of surface to be cut as compared with thepower available inthe machine which is to be used, and also on thestrength and rigidity of the workpiece itself. Since broaching tools areexpensive and have been limited by their design to the performance of aparticular operation, broaching has only been employed where a largenumber of identical parts must be finished. In addition, broachingmachines are either limited in their range of operations by reason oftheir limited stroke, or, if designed to take a long broaching stroke,are of excessive size and cost. In a few instances, broaching machineshave been constructed to make a plurality of successive strokes with thesame broach on the same workpiece in order to reduce the size of themachine required to cut away metal to a given depth, but no satisfactorymeans for adjusting thedepth of cut per tooth has been suggested and,therefore, no one has devised a practical machine which may be usedeconomically for machining only a few pieces of one kind, as isfrequently required in job shops or tool making.

Accordingly, it is the general object of the invention to provide asurface broaching machine capable of performing a wide range ofbroaching operations with a single broaching tool in order to avoid thenecessity of securing a special tool for each difierent operation.

Another object is to provide a surface broaching machine which willautomatically remove any desired depth of metal by repeated. strokes ofa relatively short broaching tool in order to reduce the size of themachine which would otherwise be required to remove. all of the metal inone stroke. Another object of the. invention is to provide a surfacebroaching machine incorporating; im-

proved means for controlling and adjusting the depth of out of eachtooth of. the tool,- as distinguished from the usualbroa'ching:operation in which the depth. of 611171 is determined solelyby the stepped relation of the tool'teeth.

Another object of the invention is to. provide a machine of the typementionedin. which upon adjustment for. the depth. of. cutv per. toothand the total depth of metal to be removed will. automaticallyperformthenecessary number of strokes requiredfito completethe broaching,operation.

Another object of the invention is to provide a surface broachingmachine of the type mentioned in which the depth of cut per tooth may bereduced during. the broaching operation in order to permit an initialrapid rough cutting operation followed, after cutting to a predetermineddepth, by a semifinishv cutting operation on the same tool. 7

Another object of the invention is to provide a machine of the typementioned adapted to make a longer stroke after the workpiece has. beencut to size in order to bring into action special finishing teeth whichdo not engage the workpiece during: the; normal roughing or.semifinishing strokes.

Other objects of the invention will become apparent from the. followinspecification, the accompanying drawings, and the appended claims:

In the drawings, Figure 1 is a vertical section through the machinetaken. generally on the line I-|' of Figure 2.;

Figure 2' is a horizontal section taken on the line 2 of. Figure 1;.

Figure 3'- is a horizontal: line 33 of Figurel; and

Figure 4 is a horizontal section taken on the line 4-401" Figure 1.

Figure 5 is a partial section and partial diagrammatic view of therewind motor and itscontrol valve.

Figure 6? is a fragmentary sectional View taken on the line 6-6 ofFigure 1.

Figure 7 illustrates diagrammatically the electrical portions of thecontrol circuit of the machine.

In the drawings; .only those portions of the masection taken. on thechine essential to anunderstanding of the invention are illustrated. Itwill be understood that the remaining structural features may be of anydesired or conventional construction.

The machine comprises a generally b'ox shaped frame. having a forwardlyprojecting portion 2 provided with a stationary support 3 for a.worktable 4 which is reciprocable' toward and away from the path ofmovement of the broaching tool in suitable ways formed in the support 3;The worktable' 4 carries anysuitable form of workholding; fixture, suchthe. fixture indic ated? genorally at 5, for holding a workpiece 6. Asbest shown in Figure 2, the machine illustrated is con- ,structedtomachine a slot I in the workpiece E and also finish the surfaces 8 ofthe workpiece. The worktable is. reciprocated by means of a Ireciprocating cylinder 9 which carries a cam plate I0 having a cam slotll shaped as best illustrated in the dotted line in Figure 2. The camslot ll receives the lower end of a pin i2 fixed in the worktable l: Forfurther details of the construction of the worktable movingmechanismreference may behad to Patent No. 2,385,119 of Benedictv Welte;gran-ted September 1-8, 1945.

3 It is sufficient only .to note here that the cam slot I l is formedwith a relatively steep portion l3 at one end for effecting a rapidinward movement of the table toward the breach, while the remaintable 4engagea pair of stationary abutments secured to the'frame of 'themachine. Each of the abutments I4 is also constructed to co-opcrate witha pair of retractable abutment screws 16 and H, the respective pairs ofabutment screws being positioned at opposite sides of the machine asbest shown in Figures 2 and 4.

The machine also incorporates a breaching ram" l8 slidable verticallyin. suitable ways carried bythe main column l9 of-the machine. Thebreaching ram, as illustrated, is in the form of a movable cylinderwhich may be consturcted in a manner more fully disclosed in theapplication of Benedict Welte, Serial No. 495,856, filed July 23, 1943,and new Patent No. 2,395,702, granted Feb. 26, 1946. The face of thebreaching ram l8 carries a tool supporting fixture 20 for a compositebreaching tool made up of the three breaches 2! 22 and 23, shown best inFigures 1 and 2. As best shown in Figure 1, the breaching tools aredivided horizontally into lower cutting sections indicated generallyat24 and shorter upper finishing sections indicated generally at 25. Aswill appear. hereafter, the finishing sections 25 are brought intoaction only after the workpiece is out to size by the cutting sections24'and thus act principally to improve the finish of the 4 completedpart.

An important characteristic of the breaching tool employed in connectionwith the present invention resides in the fact that the teeth of boththe upper and lower portions are not stepped in the usual fashion, butonthe contrary project equal distances from the axis of movement of thebreaching ram. The cutting operation of the teeth is achieved by feedingthe work in toward the breaching tool :during the breaching stroke andconsequentlythe depth of cut per tooth is controlled by the rate of suchinward feed. This mode of operation is made possibleby reason of thefact that the means for feeding the Worktable into the breach during thecutting stroke incorporates an irreversible or self-locking cam slot Hwhich positively advances the table independent of the reaction of theforce exerted upon the workpiece by the breaching tool. Means areprovided for positively controlling the rate of inward feedindependentof the magnitude of the forces involved. This means comprisesmechanism for rotating the feed screws at the desired rate of speed.Since the screws are, themselves, irreversible or selflocking helicalcams it is apparent that the combination of the hydraulically operatedirreversible cam H and the rotating screws I3 and I1 positively controlthe position and rate of advance of the table regardless of the forceexerted on the work by the breach.

To insure that the depth of out per tooth is positively maintained, thescrews I6 and I! are mechanically driven by the breaching ram. As

best shown in Figure '3, the breaching ram l8 carries a verticallyextending rack 26 which is in constant mesh with a pinion 21 fixed to ashaft 28 journaled in suitable bearings 29 and 30 carried .by the frameof the machine. Shaft 28'has splined thereto a dog clutch element 3|adapted to ce-operate with a mating dog clutch That is to say, thereaction of 32 fixed to a shaft 33 journaled in the righthand side wallof the machine. The dog clutch element 3| may be slid to the left fromthe positien shown in Figure 3 by means of shifter fork 34 actuated by ahydraulic piston cylinder unit *35 to disengage the shafts 28 and 33.Suitable means are provided to cause such disengagement at the end ofeach downward or. cutting stroke of the ram and to re-engage the clutchelements 3! and 32 upon completion of the upward or returnmovement ofthe ram. The clutch elements 3! and 32, in combination with thepistonand cylinder unit 35; constitute a one-way drive-connectionbetweenthe rack 26 and'the shaft 33.

The outer end of the shaft 33 terminates with- .in an external housinghaving a removable cover 36, and carries a gear 31. The gear 31 mesheswith a gear 38 likewise located within the external housing. Gear 38 isfixed to a shaft 39 which extends entirely across the machine and isjournaled adjacent its ends in suitable bearings 40 and 4|. Fixed to theshaft 39 is a pair of worm gears 42 and 43 which drives,respectively,,the two pairs of abutment screws 16 and ll..

Since the construction of each of the two pairs of abutment screws isidentical except as here.- after expressly pointed out, only theright-hand pair, as viewed in Figures 2 and 4, need be described. Asbest shown in Figure l, the worm gear 43 meshes with a-worm wheel 44,which in turn carriesa gear 45. The worm wheel 4 4-a'nd gear 45 arecarried by asplined shaft 46 which is fixed at its forward end to therear endef the abutment screw l1 and are held against axial movement bymeans of the arms of a generally fork-shaped support 41 which carriesthebearings for the splined shaft 46.

The abutment screw is threaded threugha sleeve 48 which is slidablymounted within a guide sleeves 49 fixed'in a suitable opening extendingthrough the main column l9 ofthe machine. A helical spring 50,positioned between the sleeves 48 and 49 adjacent their rearward ends,normally acts tohold the sleeve 48 together with the abutment screw' l!and the splined shaft 46 in their forward position illustrated inFigure2. Further forward movement of the sleeve 48 is preventedby means of apair of lock nuts 5| secured to'the'rar end of the sleeve 48 .andbearing against the rear. end of the sleeve49.

Thesleeve 48 is movable rearwardly under the influence of a pressureapplied to the forward end of thesc'rew H to .a positionin which theshoulder, '52 at the forward end of the sleeve, engages the forward endof the sleeve 49. ,This movement occurs as the worktable'moves intobreaching position, thereby operating a lever v53 pivoted to the columnof the machine and having one end engaging .thelrear end of sleeve '48,.This movement of'the lever 53 is relied upon .to'opera'te a controlinstrumentality which starts the breaching ram onits downward or cuttingstroke. Since the worktable cannot move toward the breach any morethan.it is'permitted to do so by the abutment screw I], it will, be apparentthat the abutment screwv l.1jcontrolslt he position of auspice?'nectionsb'etweenrack 2'5 and theabutment screw 1"! previouslydescribed,"the screw will be slowly rotated in a directionto permitprogressive advance of the worktable throughout the breachin stroke.The-speed'o'f such advance may be readily adjusted by changing therelative sizes of the gears 31 and 38, which are conventionalchangespeed gears of a type available on the market in stam iard sets*at relatively low cost. 'The"' arrangement is such that a sta'ndardsetof changespeed gears will provide a full range of adjust- "ment ofthedepth of cut per tooth. Suchad'just- *which are so stepped as to out asmaller depth per tooth to bring the part to approximately final sizewith a finer finish. In order to achieve the same results with thepresent mechanism there is provided an auxiliary slow-speed abutmentscrew 'lliwhich is not engaged by the abutrnent M on the table untiljust before the abut- 'ment l t-engages the fixed abutment 15. Theabutment screw W has secured at its rearward enda splined shaft section:56 fitted within a splined opening in the sleeve 57 of a gear 58 which,in turn, is "in mesh with the previously mentioned gear 45. The sleeve51 of gear 58 is "journaled within the fixed bearing '59. On-startingthe machine from the position shown in qFigurel, both of the feed screwsl6 and 11 will beprogressively withdrawn during each successive downwardor broaching stroke, but the screw I6 will be withdrawn at a slowerratethan the screw 11, with the result that screw i! will eventuallyovertake screw l6 and the latter will then actas thecontrollin'gabutment for the worktatble. I 'The parts may be permanentlyarrangedsothatthe abutment screw l fi takes control when'the abutment l4isspaced from the fixed abutment 'IEby the total depthof cut requiredtoremove the inferior finish produced by the roughing or "heavy cuts."Since this amount is normally less than the'totaldepth of cut'perstroke the reduced feed will o'rdin'arilybegin during the'last stroke ofthe lower portion of the broach.

The abutment screws 16 and H are duplicated on the opposite side'of themachine in order to "provide abutments for the table locatedat'oppositesides of the pointof application of the tablemoving force in order-toprevent any tendency "of 'thetable to cook. The structure andfunctioning of the second setof abutment screws is identical to thatjust described except that the initial free sliding movement of the'internallyscrew threaded sleeve for the second abutment screw -I'lperforms no function, and therefore may be omitted if desired;

After the fixed abutments 14 and 'l engage no further, inward movementof the table willoccur, but the loroaching ram will continue its "strokeuntil it is completed. The teeth *on broach 24 "which pass over the workafter the fixed abut- "ments-engage each other will perform'a finishin'goperation in thesame manner as the uns'tepped finishing teeth ofaconventional broah.

:6 in addition they finish true parallel with the pat-lief movement ofthe breach, a result that lcann'ot lae achieved while the work is beingfed into the br-oac'h. However, "in order to provide a betteri'lnish andalso to take care of the possibility that theabu'tments M and I5 engagejust at theend of the normal broache ing stroke of breach 2%,the-machine is construct- =ed to -provide "a final stroke of extralength in "order to bring into action the short fini'sh br'oac'h section25 after the abutments engage each other.

This result is accomplished in the fol-lowing manner:

The-machine is provided with a shaft 80 which is rotated in onedirection "upon completion 0f the breaching strokeof the ram, and inthe'op- 'posite direction upon completion of the return stroke, andthroughsuch rotation operates a control ins'trumentality to initiate thetable return and'the table advance movements respectively. In addition;the shaft :80 "will operate any suitable control instrumentality to stopthe downward movement of the broaching ramupon completion of itsbroaching stroke. The shaft'80 is journaled in asleeve 82 mounted inthe'main column o'f the machine and'carries a bifurcated lever 83 of-con-' ventional construction adaptedto co-operate with "three trip dogs'84, 85, and 86 -mounted on the breaching ram. In the normal runningposition of the shaft 80, illustrated in Figure -1, the-shaft is rotatedin a clockwise-direction by trip dog at completion of the-breach returnmovementof the ram, and in 'a counterclockwise direction by the trip dog-85 upon completion of the normal breaching strokeof the ram. Suitablemeansare provided for retracting the shaft 80 after the'a'ffixedabutments I4 and 1 5 engagaand thereby shifting the bifurcatedlever-83 out of the path of movement of the trip'dogBB and into-the pathof *movementof the trip dog 8'fi. Upon suchshi'ftpf "the shaft 'sfl theram will not stop at the-'endof its breaching stroke'but will continuedownwardly carrying the finishing broach section 25 past the work untilthe trip dog 86 engages" the lever 83, and thereby rotates the shaft 80in its counterclockwise direction. It will be noted that the jtrip dog 81 is of suflicient width to engage and operate the lever 83 in bothpositions of adjustment of the shaft 81!. A lever 81 pivoted to thecolumn of the machine'at 88 and having one end connected to the shaft 80is normally "actuated by spring 89 in a directionto'holdthe shaft--8llin the normalrunning position illustrated. A solenoid 90 'connectedtothe opposite endof thelever '81 will, when energized, rotate theleverjtl Lina .counterclockwise direction and retract the shaft 80 to *aposition *in which it permits the long stroke of the ram.

At theend of *thecomplete broachin'goperation 'the abutment screws arereturned to their outer -or starting positions by means of a "hydraulicmotor which drives a gear tl that is in constant mesh with a gear "6-2on shaft :39. This rewindoperation, which occurs during a period whenthe clutchelements 3 and 32 are disen-f gaged, is controlled by means'-of a solenoid valve illustrated in Fig. 5. As' thereshown, the controlvalve 63 is connected by means of 'a line 5-4130 the inlet of the motor60 and by conduit to the'out'het. The conduit communicates with "-0.portfifi, while conduit 65 communicateswith :a port 81 in the valvecasing. The valve spool "indicated generally "at 68 -is provided withthree lanus 59 ill), and ll.

I v A The valve casing isjell'so provided with a port 12 in consta'ritc'cmmmiithe workpiece race to a cation with the tank or other suitablesource of liquid at low pressure and a port I3 which is in constantcommunication with the pump or source of ..,communication under highpressure. The tank port '12 is in constant communication with a fifthvalve port I4 through dotted line passage- .way indicated in Figure 5. I

The spool 68 is normally held in its central position illustrated bymeans of a spring centering device of conventional constructionindicated.

generally at I5, and the spoolmay be shifted in either direction fromits central position by means of one or the other of a pair of solenoidsl8 and 'Il. In the central position of spool 68 ports 72 and Mareblocked but ports 66 and 61 are connected together and to the pressureport 13 by means of the slots I8: and 19 in the land 10. Consequently,under these conditions the .pressure applied to both sides of the motor60 is equalized, and if the gear BI is rotated incident to movement ofthe broaching ram the motor will act as a pump for circulatingliquidfreely through the valve 63 and back into the opposite side-of themotor.

When it is desired to effect a rewindof the abutment screws, solenoidTI, is energized thereby pulling the spool 98 to the right into aposition in which the land 18 blocks communication between ports 67' andI3, and opens communication between port 67 and .port 121. Under thesecon-- ditions fluid under pressure will pass through the ,valve and theline 64 to the motor 60 and will operation but to block rotation of therewind motor in order to absorb the momentum of the parts connected toit. This is accomplished by de-energizing solenoid TI and momentarilyenergizing solenoid Hi at the instant that the abutment screws projectto the desired degree. Energization of solenoid I pulls the spool 68tothe left into a position in which land l0 blocks communication betweenports 13 and 66, and land II completely blocks port 61.. This not onlycuts off the admission of fluid to pressure through theline 64 butblocks the discharge of fluid through line 85, and consequentlypositively stops rotation of the motor. Assoon as the motor has beenbrought to a stop in this manner, which requires but an instant,solenoid T8 may-be deenergized permitting return of the spool to itscentral position. This de-energization of. solenoid I0 is necessary inorder to permit free'rotation of the motor 60 during the breachingstroke.

A control slide 9i, shown best in Figure 2, is connected to the rear endof the splined shafts 46-for movement therewith and carries suitablecontrol instrumentalities responsive to movement of the slide forcontrolling energization of .the

long stroke solenoid 90 and the rewind solenoids TI and I6. Theseinstrumentalities may also effect a final stoppage of the machine uponcompletion of the broaching operation. 9 The entire .cycle of operationof the machin may be controlled automatically by any suitable hydraulic,electric, or hydroelectric circuit. For example, control of theoperation of the machine may be accomplished by means of the hydrauliccircuit disclosed in the application "of Benedict Welte serial No.491,573, filed June 21, 1943, with the changes and additions hereinafterpointed out. Thus, the machine is provided with astarting handle 92connected by-means of a. rod 93 to a starting valve 94 which correspondsto the starting valve 2I5 of the aforementioned application. This valve,as pointed out in greater detail in said application, incorporates meansfor returning, the valve to neutral position upon release of thestarting handle. A lug 95 secured to the rod 93 is adapted upon movementof the starting handle to neutral position to engage and close a switch96 which is incorporated in the hereinafter described electricalcircuit.

The machine is also provided with a valve 91 r which corresponds to thevalve 2H5 of the aforementioned application. The stem 98 of the valve 91is shifted to the left, as viewed in Figure 1, by the aforementionedlever- 53 under, the influence of sleeve 48 of the abutment screw I!when the table moves into breaching position. This movement of the stem98 also rotates a bell crank lever 99 in a counterclockwise direction,as shown in Figure l. The bell crank lever is connected by means of alink I00, a lever IOI, a shaft I02, a lever I03, and a link I04 to abell crank lever I05, which is pivoted to the frame of the machine inthe vicinity of the cam slide I0 of the table cylinder 9. As'a result,counterclockwise rotation of the bell crank lever 99, as viewed inFigure 1, shifts the bell crank lever I05 in a clockwise direction, asviewed in Figure 6. When the cam slide I0 moves to the position in whichit fully retracts the table 3, a dog I01 on the cam slide engages androtates the bell crank lever I05 in a counterclockwise direction,thereby returning the bell crank lever 99 and the stem 98 of valve 91 tothe position illustrated in Figure 1. It will benoted that forwardmovement of .the sleeve 48 of screw H has no effect upon the cam slide I0 and the switch closed when the table reaches its outermost position.This switch is also incorporated in the hereinafter described electricalcircuit.

The previously described control shaft is connected to the stem of adual rotary valve I09 which corresponds to the dual valve 2I 1-2I8 ofthe aforementioned Welt application.

I In order to operate the clutch actuating cylinder and piston unit 35of the present application in proper sequence, line H0 leading to thelefthand end of the cylinder, as viewed in Figure 3, is connected toline I44 of the aforementioned application while line I I l leading tothe opposite end of the actuator 35 is connected to line I45 of saidapplication. All the remainder of .thehydraulic circuit of theaforementioned Welte application may be employed without change, exceptthat the hydraulically operated indexing mechanism disclosed in saidapplication for controlling the position of the spool 32 'l of stopvalve 326 is omitted, and in lieu thereof the spool 32'! is shifted tothe right against the action of spring 340 upon energization of asolenoid-under the control of the electrical circuit illustrateddiagrammatically in Figure 7 of the present application where thesolenoid is indicated by the numeral IIZ.

Referring to Figure '7, the electrical control circuit comprises a pairof main electrical conduits H3 and H4 which are connected to anysuitable source of electrical potential. Connected I 11 a the tablefeeds in), a return of the table to starting position'and a return ofthe ram to starting position.

As previously indicated, relay I29 will be energized to open contact I30at the start of the abutment screw rewind operation which occurs as soonas the worktable reaches its outermost position after contact of thefixed abutments. I4 and I5. The opening of contact I30 de-energizes therelay I39, thereby breaking the holding circuit I20a and de-energizingthe solenoid H2. As a result, upon completion of the broach returnstroke which starts simultaneously with the rewind operation,.themachine will come to an automatic stop and cannot be restarted except byoperation of the starting handle 92, and only then after the rewindoperationhas completed.

It is apparent that there is provided, in accordance with the presentinvention, a surface broaching machine which, with a single permanentbroaching tool, may be employed in a tool room or in a job shop on theproduction of a wide variety of parts. For example, one relatively wide,fiat broach may be used for all types Of flat surfacing operations. Tocut grooves it is necessary to provide a broach of the proper width, butthis may be done in many cases by a combination of two or more broachesof narrow width arranged to cut successively on each stroke. It is onlynecessaryto locate an appropriate surface broach of the unstepped typepreviously mentioned on the ram and adjust the limit switch dogs I 26and I35 to control the total depth of cut, and the machine will operateautomatically through whatever number of strokes are required to removemetal to the desired depth, following which it will make a final strokeof additional length to finish the part. and then come to a stop. Justprior to or immediately after the stoppage of the machine, the rewind ofthe abutment screws to their initial position will be completed and themachine will be in condition for restarting. If necessary, the depth ofcut per tooth may be readily adjusted by substituting a different set ofchange-speed gearsfor the gears 31 and 38. No other changes oradjustments on the machine are required.

The unstepped broach employed by the machine is much easier and lessexpensive to manufacture than a conventional surface broach, and whenused in the present machine is applicable to a wide range of operationsas compared with a conventional broach.

An important feature of the machine resides in the provision of anirreversible drive for feeding the worktable into the broach during thebroaching stroke, in combination with means other than the broach forresisting movement of the worktable toward the broach in order to takeup all play in the drive mechanism and thereby avoid chatter. While itis preferred to utilize the means for resisting table movement tocontrol the speed of infeed, it is apparent that the speed may becontrolled by controlling the speed of the table driving motor in whichevent the resisting means need only exert sufficient force to preventchatter. Likewise, whil it is preferred to maintain the desiredsynchronous relation between the table feed and the ram movement byinterlocking the two in some manner, satisfactory results can beachieved by maintaining the movement of each at a constant speed in anysuitable manner.

'Another important feature of illustrated embodiment of the inventionresides in the fact that all of the forces involved in the feed of thebroach into the work are direct compression forces against solidabutments. Consequently, there is no possibility of tool chatteroccurring due to yielding of .or play between any of the structuralparts. While it is preferred to employ one or more screws, such as thescrews I6 and IT, to act as movable abutments for the table, it isapparent that any other form of self-locking cam driven by the broachingram or otherwise will serve the same purpose. For the sake ofsimplicity, it is preferred to employ removable change-speed gearing forchanging the depth of cut per tooth, but it is obvious that any form ofpositive variable speed transmission mechanism may be incorporated inthe machine if desired.

Other modifications and alterations in the detailed construction of themachinemay be indulged in without departing from the spirit of theinventon or the scope of the appended claims.

What is claimed is:

1. In a surface broaching machine, a broaching ram, a work supportingtable mounted for movement toward and from the ram, means for moving thetable toward the ram, an irreversible mechanical drive connectionbetween said means and the table, means for resisting movement of thetable toward the ram, one of said means having a constant speedcharacteristic, and means for moving the broaching ram through abroaching stroke during movement of the table toward the ram to effect abroaching operation.

2. In a surface broaching machine, a broaching ram, a work supportingtable mounted for movement toward and from the ram, means for movingthe'table toward the ram, an irreversible mechanical drive connectionbetween said means and the table, means for resisting movement of thetable toward the ram, the movementof one of said means beingsynchronized with that of the broaching ram; and means for moving thebroaching ram through a broaching stroke during movement of the tabletoward the ram to effect a broaching operation.

3. Ina surface broaching machine, a broaching ram, a work supportingtable mounted for movement toward and from the ram, means for moving thetable toward the ram, an irreversible mechanical drive connectionbetween said means and the table, means for resisting movement of thetable toward the ram, means for moving the broaching ram through abroaching stroke during movement of the table toward the ram to effect abroaching operation, and means to positively stop movement of the tabletoward the broaching ram during the broaching operation, said means formoving the broaching ram being effective to continue a broaching strokeafter the table has stopped.

4. In a surface broaching machine, a broaching ram, a work supportingtable mounted for movement toward and from the ram, means for moving thetable toward thefram, an irreversible mechanical drive connectionbetween said means and the table, means for resisting movement of thetable toward the ram, one of said means having a constant speedcharacteristic, means for moving the broaching ramthrough a broachingstroke during movementof the table toward the ram to effect a broachingoperation, and means to positively stop movement of the table toward thebroaching ram during the broaching operation, said means for moving thebroaching ram being effective to continue a broaching stroke after thetable has stopped. v

5. In a surface broaching machine, a broaching ram, a work supportingtable mounted for movement toward and from the ram, means rer moving thetable toward the ram, an irreversible mechemical drive connectionbetween said means and the table, means for resisting movementof thetable toward the ram, the movement of one of said means beingsynchronized with that of the breaching ram, means for moving thebreachin g ram through a breaching stroke during movement of the tabletoward the ram to efiect a breaching operation, and means to positivelystep movement of the table toward the breaching ram during the breachingoperation, said means for moving the breaching ram being efiective tocontime a breaching stroke after the table has stopped.

In a surface breaching machine, a reciproeating breaching ram adapted tocarry a breachihg tool, a work supporting table mounted for movementtoward and from the path of movement of the ram, means for moving theworktable toward the ram and exerting a force on the table during thebreaching stroke suflicient to overcome the thrust of the breachingtool,

means forming an abutment to limit movement of the worktable toward theram, and means for shifting said abutment means during the breachingstroke of the ram in order to permit said first means to feed the worktoward the ram during the breaching stroke.

'7. In a surface breaching machine, a reciproeating breaching ramadapted to carry a breachin'g tool, a work supporting table mounted formovement toward and from the path of movement of the ram, means formoving the work table toward the ram and exerting a force on the tableduring the breaching stroke sufficie'nt to overcome the thrust of thebreaching tool, means independent of the breaching tool forming anabutment to limit movement of the work'- table toward the ram when thetable reaches breaching position, and means independent of the forceexerted on the work by the breaching tool and of the force exerted onthe abutment by the table for shifting'said abutment means during thebreaching stroke of the ram in order to permit said first means to feedthe work toward the ram during the breaching stroke.

8. In a surface breaching machine, a reciproeating breaching ram adaptedto carry a broaching tool, a work supporting table mounted for movementtoward and from the path of movement of the ram, means for moving theworktable toward the ram and exerting a'force on the table during thebreaching stroke sufficient to overcome the thrust of the breachingtool, means forming an abutment to limit movement of the worktabletoward the ram, and means driven by the ram for shifting said abutmentmeans dur ing the breaching stroke of the ram in order to permit saidfirst means to feed the work toward the ram during the breaching stroke,arid means for varying the rate of feed.

9'. In a surface breaching machine, a reciprocating breaching ramadapted to carry a broaching tool, a work supporting table mounted formovement toward and from the path of movement of the ram, hydraulicallyoperated means for moving the table towardthe ram and exerting a forceon the table during the breaching stroke sufficient to overcome thethrust of the breaching tool, a cam type abutment for limiting movementof the worktable toward the ram-,said cam type abutment means having anefiectiv'e angle such that no force exerted by the table on the abut- 14ment means will move said abutment means, and means for operating'theabutment means during the breaching stroke of the ram in order to permitsaid hydraulically operated means to feed the work toward the breachduring the breaching stroke.

10. In a surface breaching machine, a reciprocating breaching ramadapted to carry a breach-'- ing tool, a work supporting table mountedfor movement toward and from the path or movement of the ram, a camiormoving the table toward the ram, said cam having a portion having aneffective angle such that force exerted on the table by the breachduring the breaching stroke cannot move the table, means for operatingthe oath to advance the table toward the ram, means forming an abutmentto limit movement of the worktable toward the ram, and meanssynchronized with the breaching stroke of the ram for shifting theabutment means during the breaching stroke of the ram in order to permitsaid cam to feed the work toward the breach 'dur ing the breachingstroke.

11. In a surface breaching machine, a recip recatin'g breaching ramadapted to carry a breaching tool, a work supporting table mounted formovement toward and from the path of movement of the ram, a cam formoving the table toward the ram, said cam having a portion havinganefiective angle such that force exerted on the table' by the breachduring the breaching stroke cannot move the table, means for operatingthe cam to advance the table toward the ram, scam type abutment meansfor limiting moveinent of the table toward the ram, said cam typeabutment means having an eiiective angle such that no force exerted bythe table on the abut: in'ent means will move said abutment means, andmeans for operating the cam abutment means during the breaching stroketo withdraw the abutment and thereby permit said table moving c'ain tofeed the work toward the breach during the breaching stroke.

i2, In a surface breaching machine, a reciprotating breaching ramadapted to ,carry a breaching tool, a work supporting table mounted formovement toward and from the path of movement or the ram, a cam formoving the table toward the ram, said cam having a portion havingeffective angle such that force exerted on the table by the breachduring the breaching stroke cannot move the table, hydraulic means foroperating the cam to advance the table toward the ram, screw operatedabutment means for limiting movement of the table toward the rain, andmeans for rotating the screw during the breaching stroke to withdraw theabutment. and thereby permit said hydraulically operated cam to feed thework toward the breach during the breaching stroke.

i3; In a surface breaching machine, a reciprocating breaching ramadapted to carry a breaching tool, a work supporting table mounted formovement toward and from the path of movement of the ram; a cam formoving the table toward the ram, said cam having a portion having aneffective angle such thatiorce exerted on the table by the breach duringthe breaching stroke cannot move the table, hydraulic means foroperatingthe. cam to advance the table toward the ram, screw operatedabutmentmeans for limiting movement of the table toward the rain, and meanssynchronized with the movement of the ram foirotatin'g the screw duringthe breaching stroke to withdraw the abutment and thereby permit saidhydraulically operated cam to feed the work toward the breach during thebroaching stroke.

14. In a surface broaching machin, a reciprocating broaching ram adaptedto carry a broaching tool, a work supporting table mounted for movementtoward and from the path of movement of the ram, means for moving theworktable toward the ram and exerting a force on the table during thebroaching stroke sufficient to overcome the thrust of the breachingtool, means forming an abutment to limit movement of the worktabletoward the ram, means for shifting said abutment means during thebreaching stroke of the ram in order to permit said table moving meansto feed the work toward the ram during the broaching stroke, andauxiliary abutment means providing a fixed stop for the table during thefinishing stroke.

15. In a surface broaching machine, a reciprocating broaching ramadapted to carry a broaching tool, a work supporting table mounted formovement toward and from the path of movement of the ram, a cam formoving the table toward the ram, said cam having a portion having aneffective angle such that force exerted on the table by the breachduring the broaching stroke cannot move the table,v means for operatingthe cam to advance the table toward the ram, means forming an abutmentto limit movement of the worktable toward the ram, means forsuccessively shifting the abutment means during each broaching stroke ofthe ram in a direction to permit said cam to feedthe worktablesuccessively toward the breach during successive broaching strokes,means for automatically efiecting repeated broaching strokes of the ram,and means for stopping the infeed of the table after the breach has cutto a predetermined depth.

16. In a surface broaching machine, a reciprocating broaching ramadapted to carry a breachin tool, a work supporting table mounted formovement toward and from the path of movement of the ram, a cam formoving the table toward the ram, said cam having a portion having anefiectiveangle such that force exerted on the table by the breach duringthe broaching stroke cannot move the table, means for operating cam toadvance the table toward the ram,

means forming an abutment to limit movement of the worktable toward theram, means synchronized with the broaching stroke of the ram forsuccessively shifting the abutment means during each broaching stroke ofthe ram in a direction to permit said cam to feed the worktablesuccessively toward the breach during successive broaching strokes,means for automatically efiecting repeated cutting strokes of the ram,and means for stopping the infeed of the table after the breach has cutto a predetermined depth.

17. In asurface broaching machine, a reciprocating breaching ram adaptedto carry a breaching tool, a work supporting table mounted for movementtoward and from the path of movement of the ram, means for moving theworktable toward the ram and exerting a force on the table during thebroaching stroke sufiicient to overcome the thrust of the broachingtool, means formin an abutment to limit movement of the worktable towardthe ram, means for successively shifting said abutment means during eachbroaching stroke of the ram in a direction to permit said tablemovingmeans to feed the worktable successively toward the ram'duringsucces-;

meansfor automatically effecting repeatedcute;

ting strokes of the ram, and means operable automatically after thebreach has cut to a predetermined depth for returning the movableabutment means to starting position and stopping the machine.

18. In a surface broaching machine, a recipro eating broaching ramadapted to carry a breaching tool, a work supporting table mounted formovement toward and from the path of movement of the ram, means to feedthe worktable progressively toward the breach during successivebroaching strokes of the ram, and means operable after a predeterminednumber of broaching strokes to decrease the rate of feed of the table ona subsequent broaching stroke. a

19. In a surface broaching machine, a reciprocating broaching ramadapted to carry a breaching tool, a work supportin table mounted formovement toward and from the path of movement of the ram, means formoving the table toward the ram during the broaching stroke, movableabutment means for limiting movement of the worktable toward the ram,means for operating said abutment means during the broaching stroke ofthe ram in a direction to permit said table moving means to feed thework toward the breach at a predetermined rate during the first portionof the broaching operation and at a reduced rate during a later portionof the breaching operation, and a fixed abutment effective to stepmovement of the table when the breach has cut to a predetermined depth.20. In a" surface broaching machine, a reciprocating broaching ramadapted to carry a broaching tool, a work supporting table mounted formovement toward and from the path of movement of the ram, means formoving the table toward the ram during the broaching stroke, movableabutment means for limiting movement of the worktable toward the ram,means for operating said abutment means successively during eachbroaching'stroke of the ram in order to permit said table moving meansto feed the work toward the breach at a predetermined rate during thefirst portion of the broaching operation and at a reduced rate duringthe later portion of the broaching operation, a fixed abutment efiectiveto step movement of the table when the breach has cut to a predetermineddepth, means for automatically effecting repeatedstrokes of the ram, andmeans for stopping infeed of the table after the table has engaged thefixed abutment.

, 21. In a surface broaching machine, a reciprocating broaching ramadapted to carry a breaching tool, a work supporting table mounted formovement toward and from the path of movement of the ram, means formoving the worktable successively toward the ram during successivebroaching strokes, means for automatically efiecting repeated broachingstrokes of the ram of less length than the length of the breaching tool,means for stopping infeed of the table after the breach has cut to apredetermined depth, means for causing the ram to make a broachingstroke of greater length after the infeed has stopped, and means forstopping the machine after said last mentioned broaching stroke.

, 22. In a surface broaching machine, a reciprocating broaching ramadapted to carry a breach ing tool, a work supporting table mounted for17 movement toward and from the path of movement of the ram, a cam formoving the table te-' ward the ram, said cam having a portion having aneffective angle such that force exerted on the table by the breachduring the breaching stroke cannot move the table, means for operatingthe cam to advance the table toward the ram, means forming an abutmentto limit movement of the werktable toward the ram, means forsuccessively shifting the abutment means during each broaching stroke ofthe ram in order to permit said cam to feed the werktable successivelytoward the breach during successive breaching strokes, means forautomatically effecting repeated breaching strokes of the ram of lesslength than the length of the broachingteol, means for stepping infeedof the table after the breach has cut to a predetermined depth, meansfor causing the ram to make a breaching stroke of greater length afterthe infeed has stopped, and means for stop-: 20

pin the machine after said last mentioned breaching stroke.

23. In a surface breaching machine, a reciprocating breachin ram adaptedto carry a breaching tool, a work supporting table mounted for movementtoward and from the path of movement of the ram, means for moving thewerktable toward the ram and exerting a force on the table during thebreaching stroke sufficient to overcome the thrust of the breachingtool, means forming an abutment to limit movement of the werktabletoward the ram, means for successively shifting said abutment meansduring each breaching stroke of the ram in a direction to permit saidtable moving means to feed the werktable successively toward the ramduring successive breaching strokes, means for automotically efiectingrepeated strokes of the ram of less length than the length of thebreaching tool, a fixed abutment for limiting movement of the tabletoward the ram when the breach has cut to predetermined depth, means forcausing the ram to make a breaching stroke of greater length after thetable has engaged said fixed abutment, means for retracting the tableafter said last mentioned stroke, means for returning the abutment tostarting position, and means for stopping the machine upon return of theram following said last mentioned breaching stroke.

24. In a surface breaching machine, a reciprocating breaching ramadapted to carry a breaching tool, a work supporting table mounted formovement toward and from the path of movement of the ram, a camformoving the table toward the ram, said cam having a portion having 7 aneffective angle such that force exerted on the 18 cating breaching ramadapted to carry a breaching tool, a work supporting table mounted formovement toward and from the path of movement of the ram, means formoving the table toward the ram during the breaching stroke, a pair ofmovable abutments for limiting movement of the table toward the ram, oneof said abutments being initially positioned closer to the table thanthe second abutment, means for moving both abutments simultaneouslyduring the breaching stroke of the ram in a direction to permit saidtable moving means to feed the work toward the ram during the breachingstroke, said last mentioned means being effective to move said oneabutment at a more rapid rate than the second abutment so that the firstabutment overtakes the second abutment during the breaching operation,and thereafter said second abutment is effective to limit movement ofthe table to a reduced rate of speed.

26. In a surface breaching machine, a reciprocating breaching ramadapted to carry a broaching tool, a work supporting table mounted formovement toward and from the path of movement of the ram, means formoving the table toward the ram during the breaching stroke, meansforming an abutment to limit movement of the werktable toward the ram,means for automatically effecting repeated cutting strokes of the ram,means for progressively shifting said abutment means during each cuttingstroke in a direction to permit said table moving means to feed thewerktable progressively toward the ram during successive cuttingstrokes, and means for stopping the machine and returning said abutmentmeans to its starting position after the breach has cut to apredetermined depth.

27. In a surface breaching machine, a reciproeating breaching ramadapted to carry a breaching tool, a work supporting table mounted formovement toward and fromv the path of movement of the ram, means formoving the worktable toward the ram during the breaching stroke, meansforming an abutment to limit movement" of the werktable toward the ram,

, means for automatically efiecting repeated cut- I ting-strokes of theram, means for progressively table by the breach during the breachingstroke cannot move the table, means for operating the cam to advance thetable toward the ram, means forming an abutment to limit movement of thewerktable toward the ram, means for successively shifting the abutmentmeans during each broaching stroke of the ram in a direction to permitsaid cam to feed the werktable successively toward the breach duringsuccessive breaching strokes, means for automatically effecting repeatedstrokes of the ram of less length than the length of the breaching tool,a fixed abutment for limiting movement of the table toward the ram whenthe breach has cut to predetermined depth, means for causing the ram tomake a breaching stroke of greater length after the table has engagedsaid fixed abutment, and means for stepping the machine after said lastmentioned 25. In a surface breaching machine, a reciproshifting saidabutment means during each cutting stroke in a direction to permit saidtable moving means to feed the werktable progressively toward the ramduring successive cutting strokes, means for stopping the inieed efthetable when the breach has cut to predetermined depth, a motor forreturning the abutment to starting position, means for starting saidmotor upon completion of the breaching movement of the abutment meansand means for blocking return movement of said abutment means when itreaches starting position.

CARL J. HALBO-RG.

REFERENCES CITED UNITED STATES manure Number Name Date 1,275,883 EmbreeAug. 13, 1918 1,467,525 Banker Sept. 11, 1923 1,867,592 Richards July19, 1932 2,203,803 Vancil et a1 June 11, 1940' 2,251,154 Nenninger etal. July 29, 1941 2,308,689 Hawley, Sr., et al. Jan. 19, 1943Certificate of Correction Patent No. 2,459,697. January 18, 1949. CARLJ. HALBORG It is hereby certified that error appears in the printedspecification of the above numbered patent requiring correction asfollows:

Column 17, line 74, claim 24, after the Word mentioned insert broachingstroke.; and that the said Letters Patent should be read with thiscorrection therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 31st day of May, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

